Related papers: Frozen to death? -- Detection of comet Hale-Bopp a…

Orbital elements of C2011 L4 (PanStarrs) Oort cloud comet, computed by MPC (Minor Planet Center, Minor Planet Electronic Circular 2012-T08), show that the closest approach to the Sun occurred on 2013 March 10th, at about 0.3 A.U., then…

We present the analysis of the polarimetric and spectral data obtained for the dynamically new comet C/2012\,J1 (Catalina) when it was at a distance of 3.17~AU from the Sun. The observations were made at the prime focus of the 6-m BTA…

We present results of imaging polarimetry of comet 2P/Encke performed on January 23, 2017 at the heliocentric (1.052 au) and geocentric (1.336 au) distances and phase angle 46.8 deg, 46 days before perihelion. Observations were made through…

We observed comet 96P/Machholz 1 on a total of 9 nights before and after perihelion during its 2017/2018 apparition. Both its unusually small perihelion distance and the observed fragmentation during multiple apparitions make 96P an object…

We have recently developed a coupled chemistry-emission model for the green and red-doublet emissions of atomic oxygen on comet Hyakutake. In the present work we applied our model to comet Hale-Bopp, which had an order of magnitude higher…

Comet 157P is a faint object with a history of being prone to unfortunate situations, circumstances, and/or coincidences. Several weeks after its 1978 discovery the comet disappeared and remained lost nonstop for twenty five years.…

We present optical observations of Halley type comet 12P/Pons-Brooks on its approach to perihelion. The comet was active even in the first observations at about 8 au. Starting at 4 au, 12P exhibited an extraordinary series of outbursts, in…

We present new analyses of the photometric lightcurve of Comet 1P/Halley during its 1985/86 apparition. As part of a world-wide campaign coordinated by the International Halley Watch (IHW), narrowband photometry was obtained with telescopes…

We present first measurements of the degree of linear polarization of distant comets C/2010 S1 (LINEAR) and C/2010 R1 (LINEAR) at heliocentric distances r= 5.9 - 7.0 AU. Observations were carried out with the SCORPIO-2 focal reducer at the…

Short-period comet P/2010 H2 (Vales) underwent a significant outburst of $>7.5$~mag in 2010 and has not been detected since that apparition. Here we report our recovery attempt of P/Vales using the 4.3-m Lowell Discovery Telescope (LDT)…

We present photometric and morphological analysis of the behavior of sungrazing comet C/2012 S1 ISON in SOHO and STEREO images around its perihelion on 2013 November 28.779 UT. ISON brightened gradually November 20-26 with a superimposed…

Distant long-period comet C/2017 K2 has been outside the planetary region of the solar system for 3 Myr, negating the possibility that heat retained from the previous perihelion could be responsible for its activity. This inbound comet is…

We present polarization images of Comet ISON (C/2012 S1) taken with the Hubble Space Telescope (HST) on UTC 2013 May 8 (rh = 3.81 AU, Delta = 4.34 AU), when the phase angle was alpha = 12.16 degrees. This phase angle is approximately…

We observed Comet C/Siding Spring using the Hubble Space Telescope (HST) during its close approach to Mars. The high spatial resolution images obtained through the F689M, F775W, and F845M filters reveal the characteristics of the dust coma.…

We report observations of comet C/2014 UN271 (Bernardinelli-Bernstein) carried out on UT 2024 March 8 and 17 at a heliocentric distance ($r_{\mathrm{H}}$) of 16.6 au using the Atacama Large Millimeter/Submillimeter Array (ALMA). The CO…

We report Spitzer Space Telescope observations of comet 67P/Churyumov-Gerasimenko at 5.5 and 4.3 AU from the Sun, post-aphelion. Comet 67P is the primary target of the European Space Agency's Rosetta mission. The Rosetta spacecraft will…

We present an analysis of the photometric and spectroscopic data of the comet C/2012 S1 (ISON) observed at the heliocentric distances of 6.21\div 4.81 AU. The photometric observations were made with the 60-cm Zeiss-600 telescope (ICAMER,…

We present visible and near-infrared photometric and spectroscopic observations of interstellar object 2I/Borisov taken from 2019 September 10 to 2019 November 29 using the GROWTH, the APO ARC 3.5 m and the NASA/IRTF 3.0 m combined with…

Comet C/2014 UN$_{271}$, alternative designation 'BB' after its discoverers 'Bernardinelli/Bernstein', and commonly referred to as UN$_{271}$, is an extreme case on two fronts, firstly its solar distance on discovery ($>$ 29 au) and…

Jupiter-family comet (JFC) P/2021 HS (PANSTARRS) only exhibits a coma within a few weeks of its perihelion passage at 0.8~au, which is atypical for a comet. Here we present an investigation into the underlying cause using serendipitous…